I read in the Monday, March 5, 2007 edition of USA Today about Walmart's push in getting HD Radio capable radios sold in their stores. What really surprised me in reading this is that HD Radio has been around since 2004, yet the first time I recall hearing of it was maybe a few weeks ago. I hear about XM and Sirius and see them advertised much more often. According to the USA Today article, HD Radio will be heavily advertised this year.
HD Radio does have the advantage over XM and Sirius by being free, all because of advertising. I would guess that more people will go to HD Radio for that fact alone. I don't always mind the advertising, but if it does bug me, I just go to another radio station that is playing something I want to hear. If I don't find anything, then I just listen to a CD.
What would be interesting, though I hardly expect this to happen, is to have an interface on these radios that allow the listener to send anonymous feedback to the station about the song that is currently playing - just like Pandora. This could give the stations the benefit of having an idea of how many people are listening at various times of the day and use those numbers for selling advertisements. It could benefit the listeners if the radio stations then alter what they play based on that feedback. I won't hold my breath on this happening, though.